Pressure cooking stove protective system



y 1950 R. s. GOLDTHWAITE 2,507,665

PRESSURE COOKING STOVE PROTECTIVE SYSTEM Filed Sept. 21, 1946 Patented May 16, 1950- UNITED PATE NT OFFICE Robert S. Giofdthwaite, Marion, Ind., assignor t0 rhenutenber Electric 00., Marion, "Ind a 'cor- 'poration im utation 'septemser 21, 19 4's, serial no. "698,543

2 Claims. I 1

This invention relates to a cook. stove and "a portable pressure cooker heated -thereby.

The chief object oi the present invention is to provide a control for discontinuing or 'redu'c the heat supply to the cooker upon attainmerit of a predetermined pressure therein. This "prevents wastage of food due to 'overcooking and, 'in'o're importantly, prevents generation of dangerous or excessive pressures.

The chief feature of the present invention re sides in providing an excess pressure operable cut-oh or control type connection between the portable pressure cooker and the cook stove heat supply, whereby the latter is automatically discontinued under cooker predetermined excessive pressure conditions.

Mostcook stoves are of thegas, gasoline, kerosene or electric heat source type and wherein the heat supply to the heating units of such a stove may be turned on or off at will, or manually regulated as by a valve or switch, respectively.

It is only recently that the use of the so-called pressure cooker (especially of the portable pot or pan type) has become Widespread. These are usually devoid of sight pressure gauges. Such cooking requires materially less time than conventional non-pressure cooking.

Present directions for the use of such cookers are, when the desired pressureis attained in the cooking vessel, to maintain it for only a relatively short interval thereafter as comparedv to prior practices.

Longer cooking thus results in overcooking and food waste. Also, longer cooking may result in excessive pressure generation so that an explosion occurs.

As stated, the present invention seeks to eliminate both these possibilities.

Other objects and features of the invention will be set forth more fully hereinafter.

The full nature of the invention will be understood from the accompanying drawings and the following description and claims:

In the drawing there is diagrammatically illustrated in vertical section, as it were, one embodiment of the invention and, more particularly, an electric stove application wherefore switches are herein illustrated, it being understood that i'or liquid or gaseous fuel, valves would be employed in lieu of switches.

In the drawing ll! indicates the top of an electric stove having opening ll therein in which is supported a heating unit l2. Current is supplied from lines LI and L2 to each of the units by switch l'5i1s'i1ally mountedon the stove front near the top thereof. T8 indicates a diagram"- m'atic representaticn'of a resistance 'he'ating unit but the invention is not necessarily restricted thereto.

Included in line It, for example, is a normally closed switch IT-'Iia, member I! being biased to closed position as by spring lib. This switch is 'hous'edfor concealed within the back splasher panel i8. Projecting through slot [9 in the top therebf is the toggle operable reset and opening member 2!! pivoted at 2| and spring 22 constrained to overceriter positioning.

Member '20 terminates within the panel adjacent the upper 'end of switch member 11. When member 20 is tilted elockwise, as hereinafter described, it assumes the dotted line position and is held therein by spring 22. At thesame time the adjacent end'oi member 20 tilts switch member l1 counterclockwise from closed circuit to open circuit position and thus holds the switch openin opposition to its constraint i'lb'.

To close the switch aforesaid it is necessary to manually tilt member 26 counterclockwise to the full line position which releases switch member I! to its constraint 'IIb, thus closing the "circuit to the heating unit resistance IS.

on the burner unit i2 is supported a vessel type pressure cooker having the main vessel 23 with securely attachable cover 24 with handle knob 25, if "desired. This cover includes a relief valve structure 26 comprised of a cylinder 21 with escape port 28, valve seat 29 and valve controlled passage 30.

In the valve structure 26 is a piston valve comprising piston 3| and needle valve 32. Port 28 is of less area than passage 30. This piston bears against load spring 33, the effective force of which is adjusted by external screw 34. The more it is screwed down the higher the pressure must rise in cooker 23 before the piston can oppose and overcome this adjustable load spring.

When such load is overcome the piston and valve rise, thus opening passage 30 fully to the cylinder 21 and the interior thereof to relief port 23 to visually and/or audibly indicate generation of the desired and predetermined pressure in the cooker.

Another port 35 of greater size than port 30 is also thus uncovered by the piston valve. This port communicates with one end of flexible tube 36, the other end of which terminates in a bellows structure 3! and the stationary end thereof. The movable end carries member 38 connected and by independent lines l3 and I4 controlled to lever 39 pivoted at 40.

The bellows and lever are concealed within the back splasher panel and juxtapositioned to switch member l1 and toggle member 20 so that, whenever the piston valve is pressure elevated, pressure is applied to the bellows to efi'ect counterclockwise tilting of member 39 so that member 20 is reversely tilted for opening the switch ll-lla.

As will be apparent, pressure application opens only this switch and even if the pressure falls the switch will still be held open by the toggle structure. The switch can only be closed when the pressure has lowered sufliciently to deactivate the bellows and when the reset member 20 has been tilted counterclockwise, as aforesaid.

It is also preferred to provide a ready disconnect connection between conduit 36 and cylinder 2'! at port 35. This may take the form of a bayonet type fixture, and same can serve as a finger piece and stop for facilitating conduit withdrawal from the panel interior and preventing full entrance thereto.

From the foregoing it will be apparent that generation of predetermined pressure in the cooker will effect automatic opening of the circuit to the heating unit. Whenever or wherever desired, a time delay device may be interposed between the bellows and member 20 or the capacity of the bellows can be so adjusted that inherent lag of the desired amount is included substantially, or all lag can be eliminated.

Another application of this invention would be to have the pressure switch connected to the cooker through a separate fitting and adjusted so as to cut oiT the current at the top setting of the pressure relief valve, thus acting only as a safety device should the operator forget to turn off the heat at the proper time.

Still another application would be similar to that described above except that the flexible to the setting of the relief valve.

While the invention has been illustrated and described in great detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character.

The several modifications described herein, as

, cut-out switch in series with the heating unit,

and means for transmitting vapor pressure from the cooker to the switch for cut-out purposes,

the said means for transmittin vapor pressure including a pressure relief valve carried by the cooker, a pressure responsive element carried by the stove, and conduit means connecting the relief valve and the stove carried means, the stove having a back panel spl'asher structure wherein the pressure responsive means is housed and an aperture through which the conduit means can freely pass, the same being storable in concealed relation by said panel and having detachable connection with the relief valve of the cooker, said relief valve including three ports, one open to the atmosphere and of lesser area than the other two, one communicating with the cooker interior and the other communicating with the conduit means, the piston and valve normally closing all three ports, and when cooker pressure actuated normally opening all three ports.

2. Structure as defined by claim 1 wherein there is provided manually adjustable load spring means for varying the load upon the piston valve for selective actuation of that valve at the selected pressure determined by that loading when such pressure is generated in said cooker.

ROBERT S. GOLDTHWAITE.

REFERENES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,756,787 Goughnour Apr. 29, 1930 1,931,190 Goughnour Oct. 17, 1933 2,308,603 Graham Jan. 19, 1943 2,392,077 Wilson Jan. 1, 1946 2,392,635 Bletz Jan. 8, 1946 2,424,393 Graves July 22, 1947 2,440,128 Sullivan Apr. 20, 1948 

